Auger bit



sept.1 2,1944. A, Q KOETT l Y2,358,077

poses.

Patented Sept. 12, 1944 poration of Ohio ApplicationA-pril e, 1943; seriarnddszgioi '3"Claims. (clins-*ifm y This invention relates"l to auger 'bits designed especially for' boring holes of relatively large'di- 'ameter in wood/and similar brous materials.

The bits are of the general type used in the jack and consist essentially of. cutting edges' having spiral utes leading from them, a threaded tapered spur or nos'efor advancing the cutting edge into the wood, and a shank at the oppositek end through which the bit is driven. While bits of the conventional type are suitable for boring hole's of relatively smalldiameter, up to about an inch, a great deal of power and effort is required to rotate bits oflarger sizes and the principal 'object of the present invention has been Vto provide `an auger bit which may be operated` in an veasy and convenient manner for drilling llarge-sized holes.

-The bits koi? thev present inventionY have the same component'partsas those used in the past, but the parts themselves are of a dilerent structurethrough which Ythe ease of operation is obtained. Briefly, the present bits consist essentially of an elongated noseor lead which throughout a portion of its length is tapered and through'- out the remainder, up to the junctureof thenose and cutting edges, V'it is of a substantially uni,

form diameter. Both the tapering and nontapering portions are threaded With a ne pitch screw thread, a thread, Yfor purposes of illustration, of the order kof thirty-two pitch or thereabouts which is appreciably nner than the threads used in the past. In the preferred form the nose itself contains a spiral ilute or several of them and the outside diameter of the i'luted body ofthe bit which continues rearwardly from the cutting edges is tapered for clearance pur- A spur,- extending forwardly beyond the cutting lip to sever bers at the circumference, is providedin the usual manner at the periphery of oneY or more `of thercutting edges to delineate the circle being cut.

By virtue of this constructionand particularly by virtue of the configuration of the nose through which the Vbit is drawn and advanced into the work, vthe amount of power or eiort required to operate the bit is but a fraction of the power required to drive a conventional bit of comparsary to employ -a lead screw of substantial pitch at the bit' nose in order that the threads could obtain the necessary'purchase inthe wood; such an arrangement is satisfactory for small size holes but as thebit diameter increases the lead screw, however heavy it may be, tears the woodr and thereby strips the threads formed in it, therethelips'lt'ovv obtain' a-cutting action; V

afte'rfacting as nothingrnore than a 'piltl where;

`by' still heavier axial'pressur'es are requiredat paradoxically; 'i' have determined that if the 'lead s'c'rew threads be'of'small pitchthe rela"- tivelyv weak' purchase obtained byv each; thread is offset by the greater' numberv f:v them. In" biting into the wood the iibers'arenot*puslied-outsideL Wisely'by the threads to such ai degree thatthey break;A they therefoef do A'not tearg' and a smooth advancingvv action is obtainedff VMoreoverg the spreading apart ofthe fibers as: the-'nose adlvances through them is algradual spreading. For drilling softerv woods likepi'ne, cypress and rthe nose need'have no flute'but'if' holes areto be drilledvin harder' woods in which Athe-*fibers are more diiiicultto separate, I have determined 'that a' flute "at the nose"provides-'clearanceanda Y cuttingact'ion which assists in impartingA to-the y able size. Heretofore it has been thought neceswooda thread complementary to that ron=th`e nose. y

While a pitch of thirty-two threads per inch is preferred in the bits of this invention, the exact thread spacing is not critical and it is of course intended that the present invention comprehend n variations-,such as twenty-eight, thirty and thir-` ty-six pitch and the like inthe advancing nose.

A typical bit constructed in accordance with the present invention is shown in the drawing in which: Y

Figure 1 is a side elevation.

Figure 2 is a View similar to Figure 1 showing a modied form of bit having a Yfluted nose.

Figure 3 is an enlarged Figure 2 Y f i Figure 4 is' a sectional viewtaken through the nose on the line 4 4, Lof Figure 2.

In the drawing, I designates the bit shank which is adapted to be heldin the chuck ofraA brace or other `suitable driving apparatus. The shank may be provided withL a flat `2 for betterpurchase of the chuck. In fact, the bits of the present invention are especially suited-to bepowerdriven at high speed through portable drill heads driven-electrically or pneumatically;` in

this respect the nose providesv a smooth gradual infeed and the cutting lips exert/a shaving rather than a biting action on the wood.

'The bodyrof the bit is designated `3 and itisv iiuted-in the usual manner as at 4. The body may be of'any suitable length depending upon kendVV View of the bit of the shankrnay be shortened and provided with a hub tapped out to screw VVdirectly on a chuck the cutting edges a circle spur 6 may be provided l Y which extends beyond the cutting edge.

The nose is indicated 4at 'l and consists of a Vsubstantially non-tapered portion 8 and a taL pered portion 9 which is in advance Vofthe nontapered portion. Throughout substantially the entire length of the nose 'l it is provided with ne pitchthreads l for the purpose previously described. The nose, at the non-tapered portion, should preferably be ofsubstantial'diameter,Y at Vleastlone-quarter inch or moreA on bits in the neighborhood of three inch over-all diameter and suitably proportioned in bits of Vother size to provide strength against bending the necessary pur- Y chase area at the-threads thereof.

In the modicationshown in- Figure 2, flutes Il yare out in spiral direction longitudinally of the nose to exert a slight cutting action in the hard woods. In this embodiment the flutes taper with the nose so that the end of it is of point- 4like configuration to enable it to enter the'work.

s infeed progresses, some ofl the materialis .spread apartby thernoseand somevmaterial is .cut away by thefcutting action of the flute edges.Y However, `the materialgnot removed is pressed to take the thread coniiguration to maintain the infeed action during drill rotation.

Having described my invention, I claim:

1. An auger bit comprising a drive shank, a fluted body extending from the shank and terminating in a lateral cutting edge and a nose axially aligned with the shank and extending from the cutting edge, said nose 'comprising a slender member having a substantially non-tapering por- Ytion adjacent the cutting edge and having a tapering portion therebeyond terminating in substantially a point, said nose having a cutting edge spiral flute cut in it longitudinally and .threaded with a ne pitch screw thread throughout substantially its length.

2. An auger bit comprising ,a drive shank, a iiuted body extending from the shank and terminating in alateral cutting edge and a nose axially` aligned with the shank and body and extending beyond said cutting edge, said nose being aV slender member having a,V substantially non-tapering portion adjacent the cutting edge, a tapering portion extending therebeyond and having a spiral flute out in it 1ongitudinally,said

thread of substantially ute presenting a cutting edge` and communicating .with a flute of said body, the said nose being threaded with a ne pitch screw thread throughout substantially-its length and having cutting'lips at its extremity whereby the nose constitutes a drill having a threaded periphery.

3. An auger bit comprising a drive shank, a -spirally fluted body extending-beyond the drive shank, said body terminating in laterally extending cuttingedges and a noseewhich is axially alignedwith said body andsaid shank and extending beyond said'cutting edges, said nose comprisingv a member having a substantially nontapering portion and a tapering portion therebeyond which terminates in `substantially a point, said nose having a cutting edge spiral flute extending longitudinally'of it and being threaded throughout substantially its length with a screw thirty-two pitch.

ALBERT C. KOETT. 

